Question about Marshall Amplification Marshall MG250DFX 100W Guitar Combo Amplifier

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Why does fuse blow when unit is powered up - Marshall Amplification Marshall MG250DFX 100W Guitar Combo Amplifier

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The output transistors PC board (smaller board) , which the heat sink is attached to near the fan, when attached the heat sink may touch the PC board traces, causing the board or transistors voltage to short. A Design defect. Or the output transistors may be burned up, replace fan, transistor s or both.

Posted on Feb 27, 2015

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I rather suspect IC1 TDA7293 is the cause of your problem. If this is the case you will need to check the speaker/s

Posted on Nov 12, 2014

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Amp keeps blowing fuses


Blowing fuses, was caused by many thing.
Short of rectifier,resistor,elco,tube heater,tube pin, and also trafo itself (primary or secondary winding). It must check step by step.
CAUTION :
THIS IS HIGH VOLTAGE AREA.
RISK OF ELECTRIC SHOCK THAT CAN KILL.
DON'T DO THIS IF YOU ARE NOT TECHNICIAN OR NOT FAMILIAR WITH VACUM TUBE CIRCUIT. THE CIRCUIT MAY STILL CONTAINS ELECTRIC SHOCK EVEN IF IF THE AMP IS NOT POWER PLUGGED.


The simple steps (see picture) are:
  1. Disconnect all connection from secondary of power trafo (PLV,PDCH,PACH and PHV).
    Power ON the amp. If fuse is not blowing,trafo is good.
  2. Power OFF the amp. Unplug the cord.
    Connect PLV1-PLV2-PLV3 (this are Bias voltage,+/-15VDC and Backlight PCB voltage) to power trafo.Power ON the amp. If fuse is not blowing,PLV circuit is good.If fuse blowing,there are parts is damage (dioda,elco,7815/7915,resistor) in this PLV circuit.
  3. If step 2 is good,go to next step.
    Power OFF the amp. Unplug the cord.
    With PLV circuit stay connected,connect PDCH 1-2 and PACH 1-2 to power trafo. Power ON the amp.
    If fuse is not blowing,PDCH and PACH circuit is good and all tubes heater/filaments are lights after a few seconds.
    If fuse blowing,there are parts is damage (dioda,elco,tube heater pins) in this PDCH/PACH circuit.
  4. If step 3 is good,go to next step.
    Power OFF the amp. Unplug the cord.
    With PLV,PDCH,PACH circuit stay connected,connect PHV 1-2 to power trafo.
    Power ON the amp. CAUTION: HIGH VOLTAGE AREA is ON.
    If fuse is not blowing,PHV circuit is good.
    If fuse blowing,there are parts is damage (dioda,elco,tube pins) in this PHV circuit.
.amp-keeps-blowing-fuses-01sk4vtrndbaaguwe2brflsj-5-0.jpg
Notes:
  • Steps had to be done sequentially from 1 to 4, not upside down.
  • If tube/heater pin is short,it can't be repair. The tube must be replacing.
  • PDCH circuit is voltage for V1-2-3-4 heater/filaments.
  • PACH circuit is voltage for V5-6-7 heater/filaments.
  • Always replace fuse with same type.

amp-keeps-blowing-fuses-01sk4vtrndbaaguwe2brflsj-5-1.jpg

Oct 02, 2015 | Peavey 6505 Plus 120W Guitar Amp Head

1 Answer

Peavey xr1200 blows 8A fuse after about one second. Old mixer, seldom moved, has worked fine for years


If it blows a fuse when powered on, it has a dead short somewhere. Old units do this when the capacitors (filters) get old and dry out. These create dead short circuits. I recommend going through the unit and change out the bad ones. They can usually be spotted easily. They look like little cans glued on the board with an "X" on top. They are usually blue, gray, or black. The X on top is a weak spot allowing the top to open or pop up when they go bad.

Mar 22, 2014 | Music

1 Answer

One side of my peavey xr86000 power mixer blew a fusework


Any unit that blows fuses needs to be serviced. Do not keep putting in fuses only for them to be blown again. Each time you put in a fuse and it blows, it will create more damage to the amplifier.

Jan 14, 2013 | Peavey XR 8600D Class D Powered Mixer

1 Answer

The fuse blows seconds after the unit is switched on. No fatal accident occurred to cause the problem.


One of the power amps has failed. Take unit in for servicing unless you are electronically adept.

Here is schematic:

http://elektrotanya.com/behringer_b2031.pdf/download.html

Scroll down to "get manual" and click on that to download. Ignore other download links.

The unit uses LM3886 power amp chips. Likely one has shorted. Use a 40 watt light bulb in series with the input power cord to act as a resetable fuse to avoid wasting fuses during troubleshooting and repair.

Jun 24, 2011 | Behringer Truth B2031a 225-watt Powered...

1 Answer

It blow my fuse every time i put a new one


NEVER replace a fuse without fixing why it blew!!! You often cause further components to blow increasing the cost of repair. It is unlikely you can DIY a repair on this unit unless you are electronically adept as there is likely component(s) within the unit that have failed. They might be in the power supply or the amp(s) within the unit.

Hopefully you know that you power ALL interconnected equipment from a single source of power. People often destroy powered speakers and mixers by powering them from receptacles at opposite end of the room and the ground bounce and spikes on power lines exceed the common mode capability of the equipment and fry the input circuits. They don't tell you about this in the user manuals... but then they get to charge you for repair... This is my word to the wise...

Dec 13, 2010 | JBL PRX618S Speaker PA Sub

1 Answer

I have Behringer pmp 2000 mixer but it burned my fuse. How can I buy it?


If the fuse blew do NOT replace it till the unit is serviced or you will burn up more components. These units will blow out from a minimum of three to 30 components when they blow.

There is weak insulation between layers of the power amp circuit board and the arcing destroys a minimum of three transistors and often many more components on the power supply board as well.

I have repaired several of these and it is a lot of work. The power amp module can be had for about $175 but it often takes out the power supply as well.

Jun 30, 2010 | Behringer Pmp3000 16 Channel Audio Mixer

1 Answer

Where can I buy a fuse and fuse holder for my Behringer pmp 3000 power mixer - can anyone tell me pleas Lyn


DO NOT REPLACE A FUSE if it blows. You will do additional damage to the unit internally.

When these blow, there is damage inside that must be repaired before restoring power.

To get an exact replacement fuse holder it is best to get it from Behringer parts. This one has a switch in it depending on which way the fuse carrier is inserted.

May 12, 2010 | Behringer Pmp3000 16 Channel Audio Mixer

1 Answer

Output fuse blowing


I don't believe this unit has an "output" fuse. The fuse is in the power line input typically.

When it blows there is usually a defect in the power transformer or the input rectifier and or filter capacitors.

Fixya is very imprecise on the model numbers of the postings here. If your unit is a tube type, then check the fuse to see if it is silvery inside. This indicates a dead short. Most of these use solid state rectifiers so suspect a shorted diode or filter cap.

You need a bit of trouble shooting electronic skill to work on this. Remember that vacuum tubes run at high voltage so great care must be used when working on these.

Mar 08, 2010 | Fender Hot Rod Deluxe Guitar Combo...

1 Answer

Blown fuse


Continued replacement of fuses without fixing the reason for them blowing MAY be doing additional damage to components in the unit.

It needs to go to a repair shop. It is likely there is damage in the power supply section or that of the power amplifier section.

Feb 28, 2010 | Marshall MG100HDFX 100-Watt Amplifier Head

1 Answer

Mackie 1604 16 Channel....when I power up it is blowing fuses...


check ur power supply unit inside...there maybe component already shorted or short circuit...whether a transistor...

Jan 03, 2009 | Mackie 1604 Vlz3 16 Channel Mixer

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